public static IAtomContainer getRelevantAtomContainer(IChemModel chemModel, IBond bond)
        {
            IAtomContainer result = null;

            if (chemModel.SetOfMolecules != null)
            {
                ISetOfMolecules moleculeSet = chemModel.SetOfMolecules;
                result = SetOfMoleculesManipulator.getRelevantAtomContainer(moleculeSet, bond);
                if (result != null)
                {
                    return(result);
                }
            }
            if (chemModel.SetOfReactions != null)
            {
                ISetOfReactions reactionSet = chemModel.SetOfReactions;
                return(SetOfReactionsManipulator.getRelevantAtomContainer(reactionSet, bond));
            }
            // This should never happen.
            return(null);
        }